I like the OP a lot, but I feel like the airport security slags would probably be more than a little suspicious upon x-raying/doing a bag check and finding a HERMETICALLY SEALED BOX.
Kind of thing that raises red flags at a glance. Honestly, I think you'd do better with the PSK-3 in a cyberleg holster, and then just Charisma + Con them into believing that the PSK-3 is part of the cyberware that's essential to making your leg (..."lost it in the Crash"...) work. Less ranks of restricted gear, certainly. And the closest you can get to a pistol disguised as part of a dialysis machine.